"song ti" and other bitmap fonts are not available even with `yes-bitmaps' applied

[Zhang Weiwu]

Binary package hint: fontconfig

Having 70-yes-bitmaps.conf replacing 70-no-bitmaps.conf in /etc/fonts/conf.d/ does not make available all bitmap fonts. Reproduce:

1) have 70-yes-bitmaps.conf set;
2) some bitmap fonts in /usr/share/fonts/X11/misc are then available in fc-list. Some others are not.

Example of those are available on both xlsfont and fc-list:
/usr/share/fonts/X11/misc/unifont.pcf.gz in xfonts-unifont package
    xlsfont says

    -gnu-unifont-medium-r-normal--0-0-75-75-c-0-iso10646-1
    -gnu-unifont-medium-r-normal--16-160-75-75-c-80-iso10646-1
    -unifoundry.com-gnu unifont-medium-r-normal--0-0-0-0-p-0-iso10646-1

    fc-list says:

    unifont.pcf:style=Regular
    unifont:style=Medium

Example of those are available on xlsfont but not on fc-list:
/usr/share/fonts/X11/misc/gb16st.pcf.gz in xfonts-base package.
    xlsfont says:

    -isas-song ti-medium-r-normal--0-0-72-72-c-0-gb2312.1980-0
    -isas-song ti-medium-r-normal--16-160-72-72-c-160-gb2312.1980-0
    -isas-song ti-medium-r-normal--24-240-72-72-c-240-gb2312.1980-0

    the font is not in fc-list.

Rationate why we need to make bitmap font available:
+------
| It should not happen that the system asks users to use scalable font instead of bitmap font
| when there is no scalable font replacement available.
+------

In the west there are san-serif, serif as main typefaces, each have an italic typefaces. These can be said of basic typefaces. The four basic typefaces in Chinese typography are:

- Song ti:
    two varients:
    low contrast "book" varient: scalable offered by ttf-arphic-uming package.
    heavy contrast title / strong varient: NO SCALABLE available, xfonts-base offer a bitmap one: "Song Ti"
- Kaiti. scalable offered by ttf-arphic-ukai package.
- Fangsong ti. NO SCALABLE available, xfonts-base offer a bitmap one.
- HeiTi. scalable offered by ttf-droid package.

The four-basics all have scalable versions in MS Windows since 95'.

As you can see some basic things only have bitmap version so far, in Ubuntu packages. It should not be too difficult to make them work.

[Aron Xu (happyaron)]

Assigning Arne to have a look.

[Zhang Weiwu (zhangweiwu)]

Hi Arne nice to see you again and see you work on this issue!

I just wish to mention that on 10.04 this issue seems still exist, can there be an instruction how to make Chinese bitmap fonts, e.g.
-isas-fangsong ti-medium-r-normal--16-160-72-72-c-160-gb2312.1980-0
usable in most software, e.g. gimp?

I also tried the instruction from
http://www.alanbriolat.co.uk/2009/04/enable-bitmap-fonts-on-ubuntu-jaunty/

[Zhang Weiwu (zhangweiwu)]

Hi. A complete solution for this problem is published here:

http://www.zhangweiwu.name/100921.html

Quote:
    Unfortunately font-config can make use of fewer encodings than X11 can do,
    thus not all bitmap fonts available to X11 will present in fc-list. After a few
    experiments it seems to me that only X11 fonts whos name string contain
    'iso' can be recognized by font-config. To make use of such fonts you need
    to convert its encoding.

To make it short, it seems this problem can be solved by shipping referred fonts re-encoded in unicode. "referred fonts" are Songti, Fang Songti. There perhaps are other fonts that should be re-encoded too.

[Zhang Weiwu (zhangweiwu)]

New discovery: If I load the font with fontforge, save it using UTF intead of the original GB encoding, then I got new files that can be listed in fc-list.

So I guess fontconfig ignores fonts encoded in GB encoding.

The easiest fix is to ask X.org to deliver these 2 fonts in UTF instead. Which would be a different bug on a different tracker (X.org instead of launchpad), right?